The present invention relates to a cabinet lock, and more particularly to a lock for a cabinet with a frameless glass door.
Cabinets include glass doors so that the items stored in the cabinet can be displayed without opening the door. Generally, there are two types of glass doors installed in cabinets: (1) framed glass doors, having the glass framed by wood or other framing material, and (2) frameless glass doors, which lack surrounding frames. An advantage of framed glass doors is that they are compatible with conventional cabinet hardware (hinges and locks) designed for attachment with screws. A disadvantage is that a significant portion of the door is not transparent because of the frame, which partially blocks the display of the materials stored in the cabinet. Also, frames are considered by some to detract from the aesthetics of at least certain cabinet designs.
Frameless glass doors have the advantage of a transparent door without the visual obstruction of a surrounding frame. However, it is more difficult to install lock mechanisms in frameless glass doors. A typical prior art lock mechanism 10 for a frameless glass door is shown in FIGS. 1 and 2. The lock mechanism includes a lock cylinder 12 supported within the glass door and a keeper or strike 28 on the cabinet. More specifically, lock cylinder 12 extends through spacing bracket 14 in a hole (not visible) in glass door 16. Mounting nut 18 is threaded onto threads 20 and tightened against glass door 16 to hold the lock cylinder 12 in place. Lock throw 22 extends from lock cylinder 12. Key 23 rotates the lock throw 22 between an unlocked position (FIG. 1) and a locked position (FIG. 2). Lock strike plate 28 is installed on cabinet frame 26 over lock strike recess 24. In the locked position, lock throw 22 extends into lock strike recess 24 formed in cabinet frame 26. When lock 10 is locked, the strike plate 28 prevents glass door 16 from swinging open by restricting the movement of lock throw 22.
Although prior art lock 10 effectively locks the swinging door 16, it nonetheless has several disadvantages. A hole must be formed in the glass door to install the lock cylinder. The hole weakens the glass, complicates the door construction, can result in glass breakage, and undesirably increases the cost of the assembly. Further, a pull (i.e., handle) separate from the lock must be installed on glass door 16 so that an operator has a handle with which to pull open the door if the key is missing.
Cabinet manufacturers have used magnetic door stop 4 to hold glass door 34 in the closed position. (FIG. 3.) Magnetic door stop 4 is installed on cabinet frame 32. Glass door 34 is bracketed between front plate 48 and rear plate 50 of prior art pull 2. The rear plate 50 is constructed of ferrous metal. When the door 34 is closed, magnets 6 of magnetic door stop 4 engage the rear plate 50 to hold the door closed.
Although the magnetic door stop effectively holds the door closed (FIG. 3), the opening process for such an arrangement causes difficulties. A user opening the door must pull hard enough to overcome the magnetic force holding the door closed. As soon as the magnets 6 release the back plate 50, the glass door swings freely so that the user must quickly counter the force previously used to overcome the magnet holding the door closed. The user frequently overcompensates to cause the door to vibrate or rattle. Such vibration or rattling energy transfers to the attached cabinet to rattle the items on display in the cabinet. This rattling displeases the user, since the items on display can be fragile and expensive heirlooms or curios. Further, users become annoyed by having to use the precise amount of opening force to barely overcome the magnet, yet minimize rattle.